Testing Extensible Design Patterns in OO Frameworks through Scenario Templates

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Testing Extensible Design Patterns in OO
Frameworks through Scenario Templates

• D.S. Sanders
• Software Verification Validation

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Design Patterns

• Proven architectures for constructing flexible
  and maintainable software
• Promotes design reuse
• Language independent
• Neither classes nor objects

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Origins Progenitors

• The Gang of Four
• Eric Gamma
• Richard Helm
• Ralph Johnson
• John Vlissides
• Collectively penned Design Patterns Elements
  of Reusable OO Software
• Written between 1991-1994 released 95

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Creational Patterns

• Abstract Factory
• Factory Method
• Builder
• Prototype
• Singleton

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Structural Patterns

• Adapter
• Bridge
• Composite
• Decorator
• Façade
• Flyweight
• Visitor

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Behavioral Patterns

• Chain of Responsibility
• Command
• Interpreter
• Iterator
• Mediator

• Momento
• Observer
• State
• Strategy
• Template Method
• Visitor

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Post Gang of Four Patterns

• Architectural Patterns
• Model View Controller
• Concurrency Patterns
• Single Threaded Execution
• Guarded Suspension
• Balking
• Read / Write Lock
• Two Phase Termination

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Memory Lane Comp 110

• Dynamic Typing
• Some or all type checking done at runtime

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More memory lane Comp 110

• Dynamic Binding
• Determining at runtime the appropriate method to
  call

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Pattern Categorization - Redux

• Static
• Does not allow for easy extension
• Behavior does not change after compile time
• Easier to test
• Extensible
• Allows functionality of the app to change
• Adds new classes to the system
• Some of the classes loaded at runtime

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Factory Method Pattern
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Factory Method Example
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Factory Method Example
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Strategy Pattern
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Strategy Pattern Example
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So much testingso little time

• Scenario Based Testing
• Method Sequence Specification (MtSS)
• Message Sequence Specification (MgSS)
• Message Framework Specification (MfSS)

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The Bank
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MtSS of Account Class and MgSS of Method Withdraw
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Message Framework Sequence Specs
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Test Cases

• MfSS Slicing
• Partition Testing
• Object Types
• Number of / Groups of Objects
• Object Input Space

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More Memory Lane Comp 380

• Stress Testing
• Boundary Testing
• Negative Testing
• Random Testing

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Compensating for Extensibility

• Testing Dynamic Typing
• Testing Dynamic Binding
• Testing Extensibility

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Testing Results
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Conclusion

• Testing Extensible Design Patterns is difficult
• MfSS will generate scenario templates which lead
  to test cases
• Use in Industry seems limited
• Source Code Credit
• Kathy Sierra, Bert Bates (Factory, Strategy)
• Collegeboard.org (GridWorld Case Study)

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